passing parameter in system.threading.timer

[sohaib_a]

I have an application in which i want to run multiple threads periodically.For this i am using the system.threading.timer in an array. When i start the timer i also want to pass a string as a parameter to the timer callback method.There is a parameter; 'state as object'.Can i pass the the string through this?

For j As Integer = 0 To m_TimerList.Count - 1
'Dim oCallback As New TimerCallback(AddressOf timer1_tick)
Dim s As String = "1"
m_TimerList(j) = New System.Threading.Timer(m_Timercallbacklist(j), New Object() {s}, 1, 5000)
k = k + 1
Next

How do i get the string in the timer callback method 'timer1_tick'

[Alan N]

Use casting as per the example on MSDN http://msdn.microsoft.com/en-us/library/system.threading.timercallback.aspx[^] Alan.

[sohaib_a]

I am still not getting it...dont know how to adapt the example for my case. Private Sub timer1_tick(ByVal state As Object) Dim j As String = DirectCast(state, String) End Sub this gives an error.

[Alan N]

Ok, what error, an invalid cast exception maybe? I don't programme in VB but I think the answer may be to pass s directly not as New Object() {s}.

m_TimerList(j) = New System.Threading.Timer(m_Timercallbacklist(j), s, 1, 5000)

Alan.

[sohaib_a]

thanks alot.that worked, Dim s as string m_TimerList(j) = New System.Threading.Timer(m_Timercallbacklist(j), s, 1, 5000) in the timer callback method... Private Sub timer1_tick(ByVal state As Object) Dim st As String = state End Sub NO casting...what is it used for anyway?

[Gideon Engelberth]

It is used for when you have Option Strict on (which you should turn on by default in the Options menu)

[Alan N]

Glad the problem is sorted now. The compiler has done an implicit cast of Object to String but if you were to specify "Option Strict On" in your code you would have had to explicitly code the cast. It's not a bad idea to code with strict on as it forces you to state your intentions more precisely, i.e. this parameter of type Object is actually a String and must not be anything else. The explicit cast does that for you. Many implicit conversions will succeed and then you can be left with a major problem debugging difficult to comprehend logic errors in your code. Option Strict On will stop many of these errors before they happen and make your code more reliable. Alan.